Biological Molecules Flashcards
What do carbohydrates, lipids and proteins all contain ?
Carbon, hydrogen and oxygen
What do proteins also contain other than carbon hydrogen and oxygen ?
Nitrogen and sulfur
What are the two types of carbohydrates ?
- simple sugars
* complex carbohydrates
Describe simple sugars
- soluble in water
- sweet tasting
- Single units of sugar (monosaccharides) or two molecules joined together (disaccharides)
- supply energy from respiration
- examples are glucose, sucrose and lactose
Describe a complex carbohydrate
- made of thousands of glucose molecules = they are polymers
- they are storage molecules-starch in plants, glycogen in animals
- insoluble so won’t affect water movement
- compacted so can store large amounts of glucose in a small place
What are proteins made up?
Many Amino acids
How many amino acid’s are there ?
20, which are joined together in different combinations to make proteins.
What does the shape of the protein help ?
The shape helps the protein carry out its job, and the shape depends on its sequence
What are the functions of proteins?
- structural molecules
- controlling chemical reactions = enzymes
- Messenger molecules = hormones
- combating disease = antibodies
- transport = haemoglobin
What effect does the low-temperature cause on proteins ?
Low temperature has no affect on shape, however it may carry out functions more slowly
What affect does high-temperature have on proteins?
High-temperature can change shape irreversibly. This means the protein cannot carry out its function-it has become DENATURED
What effect does extreme pH have on proteins ?
They become denatured
What are the functions of lipids ?
- Hormones
- insulation
- buoyancy
- Energy store
- blubber
- protection of organs
- main component of cell membrane
What are fats and oils ?
Types of lipids
What are lipids made up of ?
Glycerol and fatty acid’s
What are the two types of fatty acids ?
- saturated fatty acid’s = FATS
* unsaturated fatty acid’s = OILS
Describe the Benedict test for glucose
- add 5 cm³ of Benedicks solution to the liquid
- heat using a water bath at 60°
- if you see a colour change from BLUE to BRICK RED glucose is present
What test is for glucose ?
Benedicts
What test is for starch ?
Iodine
Describe the iodine test for starch
- add 5-10 drops of iodine solution to the substance
* it’s starch is present you would serve a colour change from BROWN to BLACK or BLUE
What controls chemical reactions ?
Enzymes
What are enzymes ?
A group of proteins. Enzymes are biological catalysts
What is a catalyst ?
A catalyst is a chemical which increases the rate of reaction without being used up itself in the reaction
What is the name for the substance the enzyme acts on ?
Substrate
What is the name for the substance produced by the reaction of an enzyme ?
Product
What two things can enzymes increase the rate of ?
- catabolic reactions - breaking down large molecules into smaller ones
- anabolic reactions - building large molecules from smaller substrates
Describe how enzymes work
- The substrate binds to the active site on the enzyme
- The active site of a particular enzyme has a specific shape which is complimentary to the shape of the substrate
- once the reaction has occurred the products do not fit the active site’s shape anymore so they are released
- after the reaction the enzyme molecule is free to catalyse the next reaction
What does binding to the active site enable the reaction to do ?
- Occur with a lower activation energy then without the enzyme. This is how enzymes are able to increase the rate of reaction
- without enzymes reactions would occur to slowly and organisms would die
What are the effects of temperature on an enzyme ?
- as temperature increases molecules have more kinetic energy therefore, they move faster. If molecules are moving more quickly, they are more likely to collide with other molecules or with enzymes. This is the reason why reactions involving enzymes happen faster at higher temperatures
- however at extremely high temperatures the shape of the enzyme is irreversibly change, this is because the thermal energy alters the active site, as a result The substrate will no longer be complimentary to the active site, this means the reaction cannot occur. We say that the enzyme is denatured
Effects of pH on an enzyme ?
• The shape of an enzyme is also dependent on pH. Each enzyme has its own optimum pH and chemical bonds hold the correct shape at the pH. A significant change in the pH would disrupt the chemical bonds and cause a change in shape, which will mean that the substrate is no longer complimentary to the active site and so cannot bind to the enzyme
Effects of surface area on enzymes ?
- enzymes will catalyse reactions more rapidly if the substrate has a larger surface area.
- This is because there is more of the substrate accessible to the enzyme and so more chance of a successful collision between substrate and an active site
Effects of concentration of substrates to enzyme
- enzyme reactions will occur more rapidly if the concentration of the substrate and/or enzyme is increased
- this is because there are more successful collisions between the substrate and an active site
